Mr Brown is off to a good start

To become leader of an established democracy without facing a public vote is a funny sort of political achievement, but an achievement nonetheless. By doggedness, machination, intimidation and persuasion Gordon Brown disposed of rivals and made his premiership inevitable.

An unchallenged succession might offend some democratic sensibilities, but constitutionally it is proper. Britain elects parliaments, not presidents. When Mr Brown becomes leader of the Labour party he will inherit a legitimate right to govern.

But an automatic mandate does not come with reserves of goodwill, a commodity traded by the ballot box. Mr Brown has a lot to prove.

He has made a good start. He launched his leadership campaign with a pledge to serve 'humbly' and to build an administration of 'all the talents', an apparent attempt to rebut the charge that he prefers solitary brooding to wide consultation. His proposal to publish a draft legislative programme ahead of the Queen's speech is sensible. His hints at greater authority for parliament and consolidation of Britain's ragged constitution are promising. That is an area where he can distance himself from Tony Blair without repudiating the substantial achievements of New Labour. Even Mr Blair's friends admit he was no stickler for the details of constitutional reform, and no fan of Whitehall protocol. Government, Mr Brown appears to be saying, will move off the sofa and back to the cabinet table.

Distinguishing himself from Mr Blair in matters of style is easy. The contrast was obvious enough in the speeches they made last week: Mr Blair was theatrical, effusive, emotional. Mr Brown was serious, cerebral and, as proved by a misplaced autocue that obscured his face from TV cameras, not much concerned with stagecraft.

Mr Brown believes his gravitas will be a welcome change from Mr Blair's breeziness, and a contrast to David Cameron's bonhomie, which he thinks is a mask over policy-making vacuity. But he is mistaken if he thinks seriousness alone will earn him the trust of voters. Unlike a Chancellor, a Prime Minister lives under relentless media scrutiny. Mr Brown's ability to perform with spontaneous charm and authority has never been publicly tested by unforeseen events.

Meanwhile, there are foreseeable problems looming. For example, US Iraq policy is caught in a feud between George Bush and the Democrat-controlled Congress, leaving no room for consultation with Downing Street. That is tricky for Mr Brown, who will want to demonstrate foreign policy autonomy from Washington while the reality is that, militarily at least, Britain cannot act alone. His approach so far has been the right one: emphasising the need for economic incentives to Sunni-Shia reconciliation. That is not a line often heard in the White House.

On the domestic agenda, Mr Brown faces trouble at the Home Office and its newborn sibling the Justice Ministry. Prisons are full. To make room for new inmates, old ones are being freed on the sly. Meanwhile, there are swathes of prisoners who should never have been jailed: women, most commonly sent down for minor non-violent offences; children - Britain is Europe's biggest jailer of under-21s; sufferers of mental illness, locked up for want of long-term psychiatric care. A new government should radically overhaul penal policy, reviewing what crimes deserve custodial sentences and adequately funding the alternatives.

Also at the Home Office is a looming row over ID cards. Their cost is spiralling and every precedent of big government IT projects suggests the technology behind them will fail. Mr Brown could spare trouble and cash, while showing respect for citizens' privacy, by ditching the scheme.

With 10 years to prepare for the job, the Chancellor surely has some policy tricks up his sleeve. He has shown, by the stealthy manner of his accession, that he is a brilliant, if secretive political operator. The need for stealth has now gone, and a new, more candid Gordon Brown is emerging. He may not face an electoral challenge, but he will have a legal mandate to govern. There are grounds to believe also that he has the skill and authority to govern well.